<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Template</title>
</head>
<body>

<div id="app">

    <span v-if="isUser">
        <!-- for指向输入框聚焦点 -->
        <label for="username">用户账号</label>  
        <input type="text" id="username" placeholder="用户账号">
    </span>
    <span v-else>
        <label for="email">用户邮箱</label>  
        <input type="text" id="email" placeholder="用户邮箱">
    </span>
    <button @click="isUser = !isUser">切换类型</button>

</div>

<script src="../js/vue.js"></script>
<script>
    const app = new Vue
    (
        {
            el : "#app",
            data : 
            {
                isUser : true,
            }
        }
    )
</script>
    
</body>
</html>